The deployment of a medical device, such as an intraluminal prosthesis, into the lumen of a patient from a remote location by the use of a delivery device is generally known. Radially-expandable prostheses can be used, for example, to repair diseased and damaged aorta such as abdominal aortic aneurysms and thoracic aortic aneurysms. For example, a stent-graft may be loaded onto a delivery and deployment device and percutaneously inserted into the body lumen of a patient in a radially-compressed configuration. Once the prosthesis is in a proper position, it may be released so that it can radially expand to engage the walls of the body lumen. Exemplary expandable prostheses may be balloon-expandable, self-expanding, or both.
In general, delivery and deployment devices for intraluminal prostheses may include means for retaining and releasing the prosthesis into the body lumen. For example, such a device may include a cover or sheath for radially retaining the prosthesis in a compressed configuration. A pusher may be provided for pushing the sheath and the prosthesis into the body lumen and for delivering the device into a desired position. To deploy the prosthesis, the sheath may be withdrawn over the pusher and the prosthesis, thereby causing the prosthesis to become exposed and to expand into the body lumen.
There is currently a demand for delivery devices that are flexible and that are capable of negotiating or tracking complex and tortuous body lumina, for example the aortic arch. Such devices should exhibit high axial flexibility or trackability. One solution to improve the trackability of such delivery systems includes designing delivery system components out of generally flexible materials. For example, the sheath may comprise a generally flexible material, such as a low-durometer polyethylene or polytetrafluoroethylene (PTFE). U.S. Patent App. No. 2008/0114435 discloses a flexible delivery system comprising a pusher having at least one generally helical score in the exterior surface thereof to provide enhanced flexibility.
While it may be practical to use highly flexible materials for some applications, such as the introducer sheath, their use may be impractical for other applications, such as the pusher. The pusher must possess a high degree of pushability and therefore must, in general, possess high column strength, particularly when it is used to push a prosthesis within the introducer sheath. In general, soft and flexible materials may not possess sufficient structural integrity or strength for pusher applications. To this end, prior art pushers have been provided that are generally rigid and consequently have poor trackability.
There are many disadvantages of using a rigid pusher. For example, rigid pushers may preclude intraluminal intervention for patients with highly complex and tortuous body lumina. Also, rigid materials may possess poor kink-resistance and therefore may be susceptible to damage. The use of rigid pushers may also adversely affect the integrity of other system components, for example the sheath. For example, a relatively flexible sheath may bend or kink in the transition region between the prosthesis and a relatively rigid pusher. Accordingly, there is a present need in the art for an intraluminal prosthesis delivery and deployment system that addresses these and other problems.